This invention relates generally to atmospheric gas burners and more particularly to such burners used in domestic cooking appliances.
Atmospheric gas burners are commonly used as surface units in household gas cooking appliances. Conventional gas burners ordinarily comprise a cylindrical head having a number of ports formed around its outer circumference. A mixer tube introduces a mixture of fuel and air into the burner head. The fuel-air mixture is discharged through the ports and ignited to produce a flame.
A significant factor in the performance of gas burners in general is the distribution of heat transferred from the burner to the cooking utensil, wherein an even heat distribution over the bottom of the utensil is desired. However, because the flame ports are disposed about the outer circumference of the cylindrical burner head, they are arranged in a circular pattern. All of the ports are thus located substantially equidistant from the center of the utensil, which means that heat is generally not evenly distributed along the radius of the utensil.
A more sensitive performance factor is the burner heating speed, which is typically measured as the time required to bring a standard cooking utensil of water to boil. Locating the burner ports close to the center of the utensil facilitates a higher thermal efficiency where there is adequate secondary air and therefore (for a specified gas input rate) a faster boiling time. Thus, heating speed can be enhanced by providing the burner head with a relatively small diameter so that the ports are arranged in a tight circle close to the center of the utensil. However, a smaller diameter burner head has greater restrictions on the amount of secondary combustion air available to the ports, leading to incomplete heat release at the ports and emissions of carbon monoxide.
One known approach for providing more even heat distribution and improved heating speed is a dual ring burner, which incorporates two separate burner bodies having individual fuel inputs. Such burners have a central burner body, which is much like a smaller version of a standard cylindrical burner head, encircled by a separate annular burner body having a larger diameter. However, the central burner body typically does not experience as much external air flow because it is completely surrounded by the outer burner body. Thus, less secondary combustion air is available, and the heat output of the central burner is limited. Other drawbacks of such xe2x80x9cdual ringxe2x80x9d burners are that they are more difficult to clean and are generally more costly than single body burners.
Accordingly, there is a need for a single body atmospheric gas burner that provides both an even heat distribution and an improved heating speed.
The above-mentioned need is met by the present invention which provides a gas burner having a spiral-shaped burner body defining an internal chamber. A plurality of ports is formed in the burner body so as to be in fluid communication with the internal chamber. Preferably, the burner body includes a substantially cylindrical hub section and an arm section that is joined at one end to the hub section and bends around the hub section.
The present invention and its advantages over the prior art will become apparent upon reading the following detailed description and the appended claims with reference to the accompanying drawings.